Valve for governor apparatus



July 7, 1942. o. N. BRYANT 2,289,239

VALVE FOR GOVERNOR APPARATUS I Filed July so, 1940 Flat. 1.

INVENTOR OZRO N. BRYANT.

ATTORNEY Patented July 7, 1942 VALVE FOR GOVERNOR APPARATUS Ozro N. Bryant, Prospect 'Park, Pa., assignor-to 'Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application July 30, 1940, Serial No. 348,362

Claims.

This invention relates'to a governor-controlled admission valve organization for a prime mover, more particularly for an elastic fluid turbine, in which each of the valves is of the diffuser type, and it has for an object to provide apparatus of this character wherein the movable plug member of each valve shall be free of vibration under all operating conditions.

A more particular object of the invention is to provide a diffuser valve wherein the movable plug member cooperates with'the converging wall portion of the diffuser to provide an initial annuiar passageway portion of the diffuser passageway, but in which the bottom surface of the plug diverges abruptly away from the diffuser convergent wall portion so as to minimize the diffuser or velocity-pressure conversion effect of theannular passageway portion and thereby prevent vibration of the plug member under certain conditions of operation.

These and other objects are effected by the invention as will be apparent from the following description and claims taken in connection with the accompanying drawing forming a part of this application, in which:

Fig. 1 is a fragmentary view, partly in section, showing a governor valve arrangement for an elastic fluid turbine wherein each of the valves is of the diffuser type;

Fig. 2 is a detail section view showing a known type of diffuser valve; and

Figs. 3, 4, 5, and 6 show diifuser valves of the improved type wherein the movable plug element is modified to avoid vibration.

In Fig. 1, there is fragmentarily shown, at It, a steam turbine having a steam chest H connected by passages I2 to suitable nozzle groups It. A movable member, for example, a lifting bar it, is arranged within the steam chest for movement upwardly and downwardly by means of rods it operated by suitable governor mechanism, not shown.

The steam chest communicates with each of the passages l2 through diffuser valves, at [6, each diffuser valve including a difiuser 11 secured in any suitable'manner to the steam chest or turbine structure and a movable plug I8. The plugs l8 have stems l9 extending upwardly therefrom and through openings 20, provided in the bar Nuts 2i and 22 carried by the upper end of each stem 19 provide abutments for contact by the upper surface of the bar.

By suitable variation of the effective lengths of the stems l9 between the plugs l8 and the abutments at the upper ends thereof a desired sequence of operation of the valves may be secured. Assuming that all of the valves are closed and thatthe bar is moved upwardly, then the valves will be opened as it engages the abutments thereof, the abutments being ordinarily adjusted for sequential operation .of-the valves to supply steam to the'diiferent nozzle groups, Assuming the turbine to be carryingits maximum load with all of the .valvesopen and'that the load drops, then the governor moves .the bar downwardly, permitting the valves to close sequentiallyunder the influence of gravity. The valves open and,

close insequence as determined by the distance of adjustment of the abutments 'from'the plugs thereof, theone having'the-shortest distance being the first to open .and the last toclose and the one having the longest distance being the last to open and the first to close.

Diffuser valves have beenmade like Fig. 2 in which the diffuser I! has aninterior wall including va portion-24 which converges from the inlet .to the throat -25 and .a .portion 26- which diverges from the latterto the outlet. The plug !8 cooperateswith the diffuser to provide a passageway including the .annular portion .27 merging intothe.portion'l28- of circular section. The plughas had a convex surface providing an annular .passageway portion-converging from the inlet regionat-Ato the/annular throat at B and then diverging from the latter to-the exit region at .C. Valves of this typehave operated satisfactorily except in instances where the diffuser exi-tpressure P2 exceedsIabout'60% o'fthe diffuser inletpressure P1, when the valve begins ,to lift away fromits seat. Under such conditions, the annular .passagewaybtween the plug IB- and the converging wall portion-T24 acts as a diffuser or venturi sothatthe pressure at B isflower than the pressure Prat C. The valveis then in unstable equilibriumland often oscillates violently with a .circular mode'of vibration. 'With the valve vibrating in this way,the' steam flow. causes forced oscillationthereof which h'as'broken valve stems and destroyed the seating surfaces.

It has been found thatifthistypeo'f valve is constructed and arranged so that the annular passageway portion "ABC has no diffuser effect .or capacity for velocity-pressure conversion, it will not oscillate, and thisis accomplished by having the valve surface diverge rather-abruptly away fromthe diffuser converging surface at the downstreamfsideof .theannularthroat at"B so as'to avoid a diffuser .or velocityepressure conversion effect'fromB .to'C sufiicientto set up vibration.

Abrupt divergence of surface of the plug with respect to the diffuser converging surface for the above purposes may be effected by plugs I'Ba and IE1) of Figs. 4 and 5, which are similar to Fig. 2 so far as convergence from the inlet region A to the throat region B is concerned, or, by a plug of the disc type, as at I80 and IM as in Figs. 3 and 6, in which case the plug has a beveled or annular surface 29 cooperating with the converging surface 24 to provide an orifice type annular passage joining the regions A and C. In Fig. 4, the rounded annular surface element 30 cooperates with the converging surface 24 to provide for the converging portion of the annular passage from the inlet region at A to the throat region at B, where it joins the periphery of the reentrant conical or annular bottom surface element 3| diverging abruptly away from the converging surface 24 or extending substantially transversely with respect to the latter, the surface element 3| being joined to the bottom surface element 32. Fig. 5 shows a structure which is similar to Fig. 4 except that, instead of a flat bottom surface element 32, the plug l8b has a convex bottom surface element 32a.

In Fig. 3, the disc plug I80 has a fiat bottom surface 33 which diverges abruptly away from the diffuser converging surface 24, and Fig. 6 is similar except that the plug [80 has a reentrant annular bottom surface element 34 providing more abrupt divergence, the surface element 34 joining the bottom surface element 35.

While the invention has been shown in several forms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof, and it is desired, therefore, that only such limitations shall be placed thereupon as are specifically set forth in the appended claims.

What is claimed is:

1. In a valve of the diffuser type for controlling the fiow of elastic fluid for a prime mover, a tubular member providing a passageway defined by a continuous and unbroken boundary surface including a convergent portion joined by a throat portion to a divergent portion. the divergent portion merging into the throat portion and the latter and the convergent portion being convexly curved in the direction of flow, said convergent portion of the boundary surface providing an annular valve seat, a plug Valve member cooperating with the seat, means for moving the .plug valve member toward and away from the seat to vary the Valve flow area and providing for lateral movement thereof to insure of its being fully seated with the seat when the valve is closed, said plug valve member having an annular surface element cooperating with the convergent portion to provide an initial portion of said passageway which is annular and having a bottom surface element peripherally joining the annular surface element and diverging abruptly away from the convergent portion of the boundary surface so as to minimize the diffuser or velocity pressure conversion effect of the annular passageway portion and consequent plug valve member vibration when the outlet .pressure of the passageway is in excess of about 60 per cent of its inlet pressure.

2. In a valve of the diffuser type for controlling the flow of elastic fluid for a prime mover, a tubular member providing a passageway defined by a continuous and unbroken boundary surface converging convexly from the inlet end to a throat and then dive g from the latter to the outlet end, said convergent portion of the boundary surface providing a valve seat, a movable plug valve member cooperating with said valve seat, means for moving the plug valve member toward and away from the seat to vary the valve flow area and providing for movement thereof radially of the axis of the passageway to insure of its being fully seated with the seat when the valve is closed, said plug having a convexly-curved annular surface element cooperating with the convexly-curved convergent portion of the boundary surface to provide an initial portion of said passageway which is annular and which converges in the direction of flow and having a bottom surface element peripherally joining the annular surface element and diverging abruptly away from the convergent portion on the boundary surface so as to avoid vibration of the valve member when the outlet pressure of said passageway is in excess of about 60 per cent of its inlet pressure.

3. In a valve of the diffuser type for controlling the flow of elastic fluid for a prime mover, a tubular member providing a passageway defined by a continuous and unbroken boundary surface converging convexly from the inlet end to a throat and then diverging from the latter to the outlet end, said convergent portion of the boundary surface providing a valve seat, a movable plug valve member cooperating with said valve seat means for moving the plug valve member toward and away from the seat to vary the valve flow area and providing for movement thereof radially of the axis of the passageway to insure of its being fully seated with the seat when the valve is closed, said plug valve member having an annular surface element cooperating with the convexly-curved convergent portion of the boundary surface to provide an initial portion of said passageway which is annular and which converges in the direction of flow and having a first reentrant and conical bottom surface element having its periphery joined to the annular surface element and joined to the periphery of a second bottom surface element and said reentrant bottom surface element diverging abruptly away from the bottom wall portion so as to avoid vibration of the plug valve member when the outlet pressure of said passageway is in excess of about 60 per cent of its inlet pressure.

4. In a valve of the diffuser type for controlling the flow of elastic fluid for a prime mover, a tubular member providing a passageway defined by a continuous a d unbroken boundary surface converging from the inlet end to a throat and then diverging from the latter to the outlet end, said convergent portion of the boundary surface providing a valve seat, a movable plug valve member cooperating with said seat means for moving the plug valve member toward and away from the seat to vary the valve flow area and providing movement thereof radially of the axis of the passageway to insure of its being fully seated with its seat when the valve is closed, said plug valve member being of the disc type and having a peripheral surface element joined by a beveled or conical surface element to a bottom surface element, said conical or beveled surface element cooperating with said convergent portion of the boundary surface to provide an initial annular portion of said passageway and said bottom surface element diverging abruptly away from the convergent portion of the boundary surface so as to avoid valve member vibration when the outlet pressure of said passageway is in excess of about 60 per cent of its inlet pressure.

5. In a valve of the difiuser type for controlling the flow of elastic fluid for a prime mover, a tubular member providing a passageway defined by a boundary surf-ace converging from the inlet end to a throat and then diverging from the latter to the outlet end, said convergent portion of the boundary surface providing a valve seat, a movable plug valve member cooperating with said seat, means for moving the plu valve member toward and away from the seat to vary the valve flow area and providing for movement thereof radially of the axis of the passageway to insure of its being fully seated with the seat when the valve is closed, said plug being of the disc type and having a cylindrical surface element joined by a conical or beveled surface element to a reentrant conical bottom surface element joined to the periphery of a bottom surface element, said conical or beveled surface element cooperating with said convergent portion of the boundary surface to provide an initial annular portion of said passageway and the reentrant bottom surface element diverging abruptly away from said convergent portion of the boundary surface so as to avoid valve vibration when the outlet pressure of said passageway is in excess of 60 per cent of its inlet pressure.

OZRO N. BRYANT. 

